The Fugue

Overview

Where did the word “fugue” originate?  In Latin, fuga means flight, fugere to flee, and fugare to chase.  The idea that one voice is chasing another fleeing voice by means of canonic imitation is apropos.  From the 14th through the 16th century imitative counterpoint pieces were given many names, including caccia, chace, canon, round, capriccio, canzona, and ricercare.  Over time, the instrumental ricercare evolved into the fugue.  Early composers of this style of music were Frescobaldi, Sweelink, Froberger, Kerll, Purcell, Pachelbel, J. K. Fischer, and Buxtehude.

While many hands contributed to the development of the fugue, most would agree that it was ultimately refined and codified by J. S. Bach (1685-1750).  His Well-Tempered Clavier (two books of 24 Preludes and Fugues in every major and minor key) and his Art of the Fugue for organ are the most celebrated examples.  Bach’s fugues represent the highest achievement in the art of polyphonic composition. 

There are just a few defining features that all fugues have in common.  They begin with a single voice stating a strong musical idea.  Two or more other voices subsequently present the same idea, while the voices that entered earlier continue with counterpoint.  The original musical ideas are developed until the end of the piece.  The exposition of the themes, or subjects, and their development comprises the fugue, which evolves through a fluid compositional process. 

Structural Features of the Fugue

The structure outlined here is drawn from the architecture employed by J. S. Bach in both books of the Well-Tempered Clavier.  Many fugues written after this exhibit similar structural characteristics.  While each fugue is unique, there are shared characteristics.  The three identifiable sections of most fugues and their components are defined below.

Exposition

The subject (S) is stated in the tonic key. It contains one or more strongly recognizable motives. It usually begins on a member of the tonic triad and ends on a strong beat. The first voice states the subject alone and is joined by the other voices as they each state the subject.  Many fugue subjects have two contrasting segments: a head and a tail. Two types of fugue subjects were identified in the 18th century.  A soggetto subject is short and simple, compared to a flowing andamento subject, which is longer and contains several ideas.

The second voice enters with the subject, usually in the key of the dominant, in any octave. This statement of the subject is referred to as the answer (A). If it is an exact transposition of the subject, it is called a real answer. If an adjustment has been made to intervals in the subject to fit the harmony of the moment, it is called a tonal answer.

The first voice continues with melodic material as the second voice enters with the answer. If this material is thematic and used consistently to accompany each appearance of the subject, it is referred to as a countersubject (CS). It is written in invertible counterpoint, and used above or below appearances of the subject.

Entries of the subject in the tonic, along with answers in the dominant, continue to alternate until all voices have entered. If the exposition is unusually short, the composer may add extra, redundant, entries of the subject and answer. Once a voice has entered, it is not generally dropped from the exposition.  After the initial statement of the subject, a composer may write a link or bridge that serves to continue rhythmic motion until reaching a favorable point for entry of another voice.

The end of the exposition occurs after all the voices have entered, usually on a strong cadence.  The exposition may end with a small amount of closing material after the statements of the subject, similar to a short codetta.  The cadence is normally in the key of the dominant if the piece is in a major key. If the piece is in a minor key, the cadence may occur on either the relative major or on the dominant minor tonality.  A multiple fugue has more than one subject, each with its own exposition.

Middle Entries

Following the exposition, a series of entries of the subject is distributed among the voices in related keys. This is sometimes referred to as the development section. The middle entries are separated by episodes. An episode consists of free material, usually containing motives drawn from the subject or countersubject.  The most common technique applied in episodes is the sequencing of fragments.  These might be inversions of the head or tail of the subject, repeated a few times, typically in a downward fifth progression. 

Often a false entry, or mock entry appears in which an incomplete statement of the subject becomes episodic. Rests are used to let the voices breathe, and to draw attention to them as they re-enter the texture.

A high point of maximum intensity sometimes occurs about three-fourths of the way through the fugue.  This climax may consist of overlapping entries of the subject in different voices, a technique known as stretto.

Closing

A fugue typically concludes with one or more final statements of the subject in the tonic key.  This is often an incomplete recapitulation of the exposition. The subjects may appear in stretto, or there may be a pedal point on the dominant.

A brief coda, or codetta, may be used to lend a sense of finality to the conclusion of the fugue.  A number of the fugues in the Well-Tempered Clavier have a short coda in a free recitative style.

Subjects and Developmental Techniques

Good subjects are made of strong, easily identifiable rhythmic and melodic motives.  They clearly establish the tonic within the range of an octave or less. Some subjects modulate, and others are highly chromatic.  The order of entries is usually governed by range of voices,  The upper voices (soprano and tenor) typically alternate with the lower voices (alto and bass), such as T-A-S-B or S-A-T-B.  This provides space for each voice to operate.  In a four-voice fugue the first and third entries in the tonic are called the subject, and the second and fourth entries are called the answer.

Fugues are by definition a very unified type of composition, since no new material is introduced after the exposition.  Along with imitation and stretto, there are numerous standard variation techniques that are applied to the motives in development.  These include inversion, fragmentation, sequencing, and rhythmic augmentation or diminution.  Alterations in rhythmic values, notes added or deleted, and retrograde versions of the subject are all common treatments.  The episodes found in the middle entry section that appear between subjects are often based on sequenced motives from the subject, with several of these variation techniques applied.  

Other Fugal Genres

Fugal techniques have been applied to movements of dance suites, sonata movements, and choral music.   The Gigue was often used as a final movement in an 18th century keyboard suite, and shared many characteristics with the fugue.  The chamber sonatas of the time typically included a movement with fugal features.  In addition to the instrumental music, many composers wrote fugal choruses.  The chorusAnd with His Stipes” is a well-known example from Messiah by G. F. Handel (1685-1759).

The term for a very short fugue is “fughetta”, and the term used for a section of a larger composition with fugal entries resembling an exposition is “fugato”.


Materials

The Structure of the Fugue (PDF)

Bach:  WTC Book I, Fugue No. II  BWV 847  (PDF)

Bach:  WTC Book I, Fugue No. VI  BWV851  (PDF

Bach:  WTC Book I, Fugue No. XVI   BWV861  (PDF)

Bach:  WTC Book II, Fugue No. V   BWV874  (PDF

Bach:  WTC Book II, Fugue No. VII   BWV876  (PDF

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